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Novel
antioxidant makes old arteries seem young again, study shows
Date:
May 6, 2014
Source:
University of Colorado at Boulder
Summary:
An antioxidant that targets specific cell structures
-- mitochondria -- may be able to reverse some of the negative effects of aging
on arteries, reducing the risk of heart disease, according to a new study. When
the research team gave old mice -- the equivalent of 70- to 80-year-old humans
-- water containing an antioxidant known as MitoQ for four weeks, their
arteries functioned as well as the arteries of mice with an equivalent human
age of just 25 to 35 years.
..........................
An antioxidant that targets specific cell structures --
mitochondria -- may be able to reverse some of the negative effects of aging on
arteries, reducing the risk of heart disease, according to a new study by the
University of Colorado Boulder.
When the
research team gave old mice -- the equivalent of 70- to 80-year-old humans --
water containing an antioxidant known as MitoQ for four weeks, their arteries
functioned as well as the arteries of mice with an equivalent human age of just
25 to 35 years.
The
researchers believe that MitoQ affects the endothelium, a thin layer of cells
that lines our blood vessels. One of the many functions of the endothelium is
to help arteries dilate when necessary. As people age, the endothelium is less
able to trigger dilation and this leads to a greater susceptibility to
cardiovascular disease.
"One of
the hallmarks of primary aging is endothelial dysfunction," said Rachel
Gioscia-Ryan, a doctoral student in CU-Boulder's Department of Integrative
Physiology and lead author of the new study. "MitoQ completely restored
endothelial function in the old mice. They looked like young mice."
The study,
published in the Journal of Physiology, was funded by the National
Institute on Aging, one of the 27 institutes and centers of the National
Institutes of Health and a leader in the scientific effort to understand the
nature of aging.
To trigger
blood vessel dilation, the endothelium makes nitric oxide. As we age, the
nitric oxide meant to cause dilation is increasingly destroyed by reactive
oxygen species such as superoxide, which are produced by many components of our
body's own cells, including organelles called mitochondria.
In a
double-whammy, superoxide also reacts directly with the enzyme that makes
nitric oxide, reducing the amount of nitric oxide being produced to begin with.
All of this means less blood vessel dilation.
Even in the
young and healthy, mitochondria produce superoxide, which is necessary in low
levels to maintain important cellular functions. Superoxide is kept in check by
the body's own antioxidants, which combine with superoxide to make it less
reactive and prevent oxidative damage to cells.
"You have
this kind of balance, but with aging there is this shift," said
Gioscia-Ryan, who works in Professor Douglas Seals' Integrative Physiology of
Aging Laboratory at CU-Boulder. "There become way more reactive oxygen
species than your antioxidant defenses can handle."
That
phenomenon, known as oxidative stress, occurs when the cells of older adults
begin to produce too much superoxide and other reactive oxygen species.
Mitochondria are a major source of superoxide in aging cells. The increased
superoxide not only interacts with nitric oxide and the endothelium, but can
also attack the mitochondria themselves. The damaged mitochondria become
increasingly dysfunctional, producing even more reactive oxygen species and
creating an undesirable cycle.
Past studies
have looked at whether taking antioxidant supplements long term could improve
vascular function in patients with cardiovascular disease by restoring balance
to the levels of superoxide, but they've largely shown that the strategy isn't
effective.
This new
study differs because it uses an antioxidant that specifically targets
mitochondria. Biochemists manufactured MitoQ by adding a molecule to ubiquinone
(also known as coenzyme Q10), a naturally occurring antioxidant. The additional
molecule makes the ubiquinone become concentrated in mitochondria.
"The
question is, 'Why aren't we all just taking a bunch of vitamin C?"
Gioscia-Ryan said. "Scientists think that, taken orally, antioxidants like
vitamin C aren't getting to the places where the reactive oxygen species are
being made. MitoQ basically tracks right to the mitochondria."
The findings
of the study indicate that the strategy of specifically targeting the
mitochondria may be effective for improving the function of arteries as we age.
In addition to improving endothelial function, the MitoQ treatment increased
levels of nitric oxide, reduced oxidative stress and improved the health of the
mitochondria in the arteries of old mice.
Story
Source:
The above
story is based on materials provided by University of Colorado at Boulder. Note:
Materials may be edited for content and length.
Journal
Reference:
- Rachel A. Gioscia-Ryan, Thomas J. LaRocca, Amy L. Sindler, Melanie C. Zigler, Michael P. Murphy, Douglas R. Seals. Mitochondria-targeted antioxidant (MitoQ) ameliorates age-related arterial endothelial dysfunction in mice. The Journal of Physiology, 2014; DOI: 10.1113/jphysiol.2013.268680
Cite This
Page:
University of Colorado at Boulder.
"Novel antioxidant makes old arteries seem young again, study shows."
ScienceDaily. ScienceDaily, 6 May 2014.
<www.sciencedaily.com/releases/2014/05/140506094940.htm>.